JPH0353715B2 - - Google Patents

Info

Publication number
JPH0353715B2
JPH0353715B2 JP55063599A JP6359980A JPH0353715B2 JP H0353715 B2 JPH0353715 B2 JP H0353715B2 JP 55063599 A JP55063599 A JP 55063599A JP 6359980 A JP6359980 A JP 6359980A JP H0353715 B2 JPH0353715 B2 JP H0353715B2
Authority
JP
Japan
Prior art keywords
frequency
video signal
circuit
signal
recording
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP55063599A
Other languages
Japanese (ja)
Other versions
JPS56159810A (en
Inventor
Chojuro Yamamitsu
Katsuhiko Yamamoto
Kunio Sekimoto
Kozo Kurashina
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP6359980A priority Critical patent/JPS56159810A/en
Publication of JPS56159810A publication Critical patent/JPS56159810A/en
Publication of JPH0353715B2 publication Critical patent/JPH0353715B2/ja
Granted legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/76—Television signal recording
    • H04N5/91—Television signal processing therefor
    • H04N5/92—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
    • H04N5/923—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback using preemphasis of the signal before modulation and deemphasis of the signal after demodulation

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Reduction Or Emphasis Of Bandwidth Of Signals (AREA)
  • Television Signal Processing For Recording (AREA)
  • Signal Processing Not Specific To The Method Of Recording And Reproducing (AREA)

Description

【発明の詳細な説明】 本発明は映像信号を磁気テープなどの記録媒体
上に記録再生する映像信号の記録再生装置に関
し、特に、狭トラツク記録・短波長記録などの高
密度記録を行なつても映像信号のＳ／Ｎを向上さ
せ、モワレなどの不要成分を減少せしめ、信号歪
を極力少なくし、高Ｓ／Ｎ、高品質の再生映像信
号を提供することを目的とする。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal recording and reproducing device for recording and reproducing video signals on a recording medium such as a magnetic tape, and in particular for performing high-density recording such as narrow track recording and short wavelength recording. The purpose of this invention is to improve the S/N of a video signal, reduce unnecessary components such as moiré, and minimize signal distortion to provide a high S/N and high quality reproduced video signal.

一般に映像信号の記録再生装置、例えばビデオ
テープレコーダ（VTR）においては、映像信号
を周波数変調（FM）して磁気テープ等の記録媒
体に記録することが行なわれる。この場合、ビデ
オヘツドのトラツク幅を狭くしたり、短波長記録
を行なうと、再生ヘツドの出力低下に起因して再
生のＳ／Ｎが低下する問題があつた。本発明者等
はこの点に鑑み先に、特開昭54−12714号にＳ／
Ｎを向上させる非線形エンコアシス技術を提案し
た。この技術を適用した映像信号記録再生装置の
一実施例を第１図に示し、従来例として概略的に
説明する。 2. Description of the Related Art Generally, in a video signal recording/reproducing apparatus, such as a video tape recorder (VTR), a video signal is subjected to frequency modulation (FM) and recorded on a recording medium such as a magnetic tape. In this case, when the track width of the video head is narrowed or short wavelength recording is performed, there is a problem in that the reproduction S/N ratio decreases due to a decrease in the output of the reproduction head. In view of this point, the present inventors first published S/
We proposed a nonlinear encoresis technique to improve N. An embodiment of a video signal recording and reproducing apparatus to which this technology is applied is shown in FIG. 1, and will be briefly described as a conventional example.

第１図において、入力端１からの映像信号は自
動利得制御回路（AGC）２により一定レベルと
され、低域ろ波器あるいはトラツプ回路３で、色
信号成分が除去され、非線形エンフアシス回路４
で、入力が小信号振幅時ほど周波数の高域が大き
く強調される。 In FIG. 1, a video signal from an input terminal 1 is kept at a constant level by an automatic gain control circuit (AGC) 2, and a color signal component is removed by a low-pass filter or trap circuit 3.
The higher the frequency range is emphasized, the smaller the input signal amplitude is.

この非線形エンフアシス回路４の出力はさら
に、従来の一定量高域周波数が強調されるエンフ
アシス回路５で、映像信号の高域が強調されたの
ち、クランプ回路６で、同期先端の周波数が常に
所望値になるようクランプされ、記録可能な帯域
に相当するレベルで信号をクリツプ回路７でクリ
ツプし、次のFM変調器８でFM変調され、高域
ろ波器９、記録増幅器１０、ビデオヘツド１１を
介して、磁気テープなどに記録される。 The output of this nonlinear emphasis circuit 4 is further passed through an emphasis circuit 5, which emphasizes the high frequency range by a fixed amount in the conventional art, where the high range of the video signal is emphasized. The clipping circuit 7 clips the signal at a level corresponding to the recordable band, and the signal is then FM modulated by the FM modulator 8, and sent to the high-pass filter 9, recording amplifier 10, and video head 11. It is recorded on magnetic tape etc.

第２図は前記非線形エンフアシス回路の一具体
構成を示しており、R1，R2は低抗、C1，C2はコ
ンデンサ、D1，D2は例えばダイオードで構成さ
れたダイオードリミツタの非線形素子である。Ei
は入力信号振幅、Eoは出力信号振幅である。第
３図はその周波数特性を示している。 Figure 2 shows a specific configuration of the nonlinear emphasis circuit, where R 1 and R 2 are low resistances, C 1 and C 2 are capacitors, and D 1 and D 2 are diode limiters composed of diodes, for example. It is a nonlinear element. Ei
is the input signal amplitude and Eo is the output signal amplitude. FIG. 3 shows its frequency characteristics.

第２図において、説明の都合上C1R1＝C2R2と
する。Ei＝大の時、ダイオードD1，D2が導通し、
その導通低抗は略々零であり、その周波数特性は
第３図ａ曲線のように略々平坦な周波数特性を示
す。又、Ei＝小の時、ダイオードD1，D2が非導
通となり、その導通抵抗は略々無限大であり、
C1，R1，R2で構成されるエンフアシス回路によ
り第８図ｃ曲線のように、大きく高域周波数が強
調される。又Ei＝中の時は高域周波数の強調も中
程度となり、第３図ｂ曲線のようになる。このこ
とは、映像信号について言えざ、平坦部などの振
幅変化が小さい領域では高域成分が大きく強調さ
れ、（第４図Ａなど参照）又、ペデスタルからホ
ワイトまでの立上りや立下りをもつような輪郭成
分では高域成分がほとんど強調されず、（第４図
Ｂ参照）、ペデスタル−ホワイト間以内の振幅を
もつ輪郭部成分はある程度高域成分が強調され
る。（第４図Ｃ参照）、このようにすればエンフア
シス回路５で高域周波数を所定値だけ強調して
も、記録最高周波数は略々、前記エンフアシス回
路５のヒゲの先端で決定され、クリツプなしかわ
ずかのクリツプで信号を記録できるので、クリツ
プによるエネルギーのそう失が少なく、再生の波
形再現がよくスミアなどの現象がない。その上、
非線形エンフアシスの分だけＳ／Ｎが向上するも
のである。 In FIG. 2, for convenience of explanation, it is assumed that C 1 R 1 =C 2 R 2 . When Ei = large, diodes D 1 and D 2 conduct,
Its conduction resistance is approximately zero, and its frequency characteristics exhibit approximately flat frequency characteristics as shown by curve a in FIG. Also, when Ei = small, diodes D 1 and D 2 become non-conductive, and their conduction resistance is almost infinite.
The emphasis circuit composed of C 1 , R 1 , and R 2 greatly emphasizes high frequencies as shown in curve c in FIG. 8. Also, when Ei = medium, the emphasis on high frequencies is also medium, as shown in the curve b in Figure 3. This also applies to video signals, where high-frequency components are greatly emphasized in areas where the amplitude changes are small, such as flat areas (see Figure 4 A, etc.). The high-frequency components of the contour components are hardly emphasized (see FIG. 4B), and the high-frequency components of the contour components having an amplitude within the range between pedestal and white are emphasized to some extent. (See Fig. 4C) In this way, even if the emphasis circuit 5 emphasizes the high frequency by a predetermined value, the highest recorded frequency is approximately determined by the tip of the whisker of the emphasis circuit 5, and clipping is avoided. Since signals can be recorded with only a few clips, there is little loss of energy due to clips, and reproduction of waveforms is good and there are no phenomena such as smearing. On top of that,
The S/N is improved by the amount of nonlinear emphasis.

又前記非線形エンフアシス回路４とは、ある限
られた記録帯域を有効に利用する点に着目したも
のである。つまり従来最大入力信号振幅が到来し
ても黒から白に立上る信号で黒の尾引きとなる反
転現象が発生しないように周波数変調範囲及びエ
ンフアシス量が定められていたが、実際上はそれ
より小さい入力信号成分が平均してみれば多く、
さらに映像信号は、ほとんど1MHz以下の部分に
エネルギーが存在し、2MHz，3MHzでは−20dB
以下のエネルギーしか存在しないため、効率的な
記録ではなかつた。このため、小信号振幅入力時
や映像信号の中高域成分のレベルに応じ、FM変
調された側帯波レベルを強調し、等価的に変調度
をあげてＳ／Ｎを向上させるようにしたものであ
る。 The nonlinear emphasis circuit 4 is designed to effectively utilize a limited recording band. In other words, in the past, the frequency modulation range and the amount of emphasis were determined so that even when the maximum input signal amplitude was reached, an inversion phenomenon that resulted in black trailing in a signal rising from black to white would not occur. On average, the small input signal components are large;
Furthermore, most of the energy in the video signal is below 1MHz, and -20dB at 2MHz and 3MHz.
It was not an efficient record because there was only the following energy. For this reason, the FM-modulated sideband level is emphasized and the modulation depth is equivalently increased to improve the S/N ratio, depending on the level of the medium and high frequency components of the video signal and when a small signal amplitude is input. be.

このように記録した信号はビデオヘツド１１か
ら再生され、前置増幅器１２で増幅され、高域ろ
波器ＢでFM変調された必要な帯域が抽出され、
リミツタ回路で振幅変動が除去され、FM復調器
１５および低域ろ波器１６でFM復調された輝度
信号を得、デイエンフアシス回路１７でエンフア
シス回路５の逆特性により、再生される変調ノイ
ズやFM変調による三角ノイズが抑圧される。こ
の高域ノイズを抑圧された映像信号は非線形デイ
エンフアシス回路１８で、記録の非線形エンフア
シスの逆変換が行なわれ、小信号ほど高域周波数
を抑圧させ、三角ノイズや変調ノイズをさらに軽
減させる。このようにデイエンフアシス回路１７
の後に非線形デイエンフアシス回路１８を設ける
と、再生時の前記ノイズが軽減された信号が非線
形デイエンフアシスに入力されるので、その回路
内の非線形素子がノイズでスレツシヨルドが変動
し、逆変換の誤動作することがなくなる長所があ
る。それゆえ、記録時非線形エンフアシス回路４
は一定のエンフアシス回路５の前に配置されるの
が望ましい。前記非線形デイエンフアシス回路１
８は例えば第５図のように構成される。入力端２
１にはFM復調された映像信号が入力され、加算
器２２で後述の負帰還信号と加算され、増幅度Ａ
でＡ＞＞１の増幅器２３で増幅され、出力端２６
に出力を得る。この出力信号は第２図に示した伝
達関数Ｇ（ｓ）の非線形エンフアシス回路２４を
介し、さらに位相反転器２５で位相反転され、こ
の信号を負帰還信号として前記加算器２２に入力
される。これにより高域周波数成分が信号に応じ
て抑圧され、三角ノイズや変調ノイズが抑圧さ
れ、映像信号エネルギーとしては元のままのＳ／
Ｎのよい再生映像信号が得られる。この信号の
Ｓ／Ｎがやや不足するような場合にはさらに、例
えば映像信号の高域成分が抽出され、抽出された
高域成分をダイオードリミツタで信号を圧縮して
ノイズ成分を得、前記映像信号に逆位相で加える
ようなノイズ軽減回路１９でノイズを軽減し、出
力端２０に再生映像信号が得られる。 The signal recorded in this way is reproduced from the video head 11, amplified by the preamplifier 12, and the necessary frequency band which is FM modulated is extracted by the high-pass filter B.
Amplitude fluctuations are removed in a limiter circuit, FM demodulated luminance signals are obtained in an FM demodulator 15 and a low-pass filter 16, and a de-emphasis circuit 17 uses reverse characteristics of the emphasis circuit 5 to reproduce modulation noise and FM modulation. The triangular noise caused by this is suppressed. This video signal with high frequency noise suppressed is subjected to inverse conversion of the recording nonlinear emphasis in the nonlinear de-emphasis circuit 18, and the smaller the signal, the higher the frequency is suppressed, further reducing triangular noise and modulation noise. In this way, the de-emphasis circuit 17
When the nonlinear de-emphasis circuit 18 is provided after the 18, the signal with the noise reduced during reproduction is input to the non-linear de-emphasis, so that the threshold of the non-linear element in the circuit fluctuates due to noise, which prevents malfunction of inverse conversion. There are advantages that will disappear. Therefore, during recording, the nonlinear emphasis circuit 4
is preferably placed before a certain emphasis circuit 5. Said nonlinear de-emphasis circuit 1
8 is configured as shown in FIG. 5, for example. Input end 2
1, an FM demodulated video signal is input, and is added to a negative feedback signal, which will be described later, in an adder 22 to obtain an amplification degree A.
is amplified by the amplifier 23 with A>>1, and the output terminal 26
get the output. This output signal passes through a nonlinear emphasis circuit 24 of the transfer function G(s) shown in FIG. 2, and is further phase inverted by a phase inverter 25, and this signal is input to the adder 22 as a negative feedback signal. As a result, high-frequency components are suppressed according to the signal, triangular noise and modulation noise are suppressed, and the video signal energy remains the same as the original S/
N good reproduced video signals can be obtained. If the S/N of this signal is slightly insufficient, for example, the high frequency component of the video signal is extracted, and the extracted high frequency component is compressed with a diode limiter to obtain the noise component. The noise is reduced by a noise reduction circuit 19 that adds the noise to the video signal in opposite phase, and a reproduced video signal is obtained at the output terminal 20.

このような記録再生によれば、例えば数dB以
上のＳ／Ｎが改善される。それゆえ狭トラツク・
短波長などの高密度記録が可能になる。しかしな
がら、記録回路や再生回路の主信号経路にダイオ
ードリミツタなどの非線形素子を用いるため、奇
数波高調波が発生し、信号歪や、不要成分が発生
し、面質劣化をある程度受ける欠点があつた。こ
れについてもう少し詳しく説明する。 According to such recording and reproduction, the S/N ratio is improved by, for example, several dB or more. Therefore, the narrow track
High-density recording at short wavelengths becomes possible. However, since non-linear elements such as diode limiters are used in the main signal path of the recording and playback circuits, there are disadvantages in that odd-numbered harmonics are generated, signal distortion and unnecessary components are generated, and surface quality is degraded to some extent. Ta. Let me explain this in a little more detail.

入力された映像信号のある周波数成分sについ
て考える。この周波数成分sが非線形エンフアシ
ス回路４を通過すると、そのs成分のある振幅範
囲においてダイオードリミツタによる奇数次歪を
発生し、周波数成分sはその成分だけでなく、第
６図に示すように（2n−１）s成分（ｎは正の整
数）を含む信号となる。この信号はエンフアシス
回路５で高域成分が強調されるので第６図破線の
ようなエネルギーとなる。この信号がFM変調器
８で搬送周波数Cにより変調され。被変調波成分
の第１下側波成分を考えると、C−（2n−１）s
と表わされる。 Consider a certain frequency component s of an input video signal. When this frequency component s passes through the nonlinear emphasis circuit 4, odd-order distortion is generated by the diode limiter in a certain amplitude range of the s component, and the frequency component s is not limited to only that component, as shown in FIG. 2n-1) A signal containing an s component (n is a positive integer). Since the high frequency components of this signal are emphasized by the emphasis circuit 5, the energy becomes as shown by the broken line in FIG. This signal is modulated by carrier frequency C by FM modulator 8. Considering the first lower side wave component of the modulated wave component, C − (2n−1)s
It is expressed as

ここで、C−（2n−１）s＜０ となる高調波成分は周波数零で折りかえされたい
わゆる折り返しスペクトラムでその周波数は、
（2n−１）s−Cの成分となる。この折り返しス
ペクトラムが記録再生系を通ると、C＞（2n−１）
s−Cの場合は周波数がC−｛（2n−１）s−C
｝
＝2C−（2n−１）sの映像信号として復調され、
C＜（2n−１）s−Cの場合は周波数が、｛（2n−
１）s−C｝−C＝（2n−１）s−2Cの映像信号
として復調され、明らかに入力された周波数の信
号sと異なる周波数の不要な信号成分が生じ、再
生画質をそこねる問題があつた。 Here, the harmonic component where C − (2n − 1) s < 0 is a so-called folded spectrum that is folded back at frequency zero, and its frequency is
(2n−1)s− becomes a component of C. When this folded spectrum passes through the recording/reproducing system, C > (2n-1)
In the case of s− C , the frequency is C −{(2n−1)s− C
}
= 2 C − (2n − 1) s video signal demodulated,
If C < (2n−1)s− C , the frequency is {(2n−
1) It is demodulated as a video signal of s- C }- C = (2n-1) s-2 C , and an unnecessary signal component with a frequency clearly different from the input frequency signal s is generated, which impairs the playback image quality. It was hot.

この不要成分は、再生系の非線形デイエンフア
シス回路内のダイオードリミツタでさらに（2n
−１）Q成分を発生し、（Qは上記不要成分周波
数）再生時にも不要成分が発生する問題があつ
た。さらに、前記折り返しスペクトラムにならな
い範囲すなわち、C−（2n−１）s＞０領域のs
成分の時は、復調された映像信号は、第６図の実
線と同様な信号として再生されることになるが、
低域ろ波器１６によりsがある値以上では例えば
３次高調波以上は大きく減衰することになるが、
再生非線形デイエンフアシス回路のダイオードリ
ミツタで、せつかく減衰した３次高調波以上の不
要成分が発生し、特にこの場合は、再生映像信号
の信号歪となる問題があつた。これは特に例え
は、マルチバースト信号やsin22Tパルス信号録
再において、正弦波が歪んだり、2Tパルスが高
調波で歪む問題点があつた。 This unnecessary component is further removed by the diode limiter (2n
-1) There was a problem in that the Q component was generated ( Q is the frequency of the unnecessary component mentioned above), and the unnecessary component was also generated during playback. Furthermore, in the range where the folded spectrum does not occur, that is, s in the C − (2n − 1) s > 0 region
When it is a component, the demodulated video signal will be reproduced as a signal similar to the solid line in FIG.
When s exceeds a certain value by the low-pass filter 16, for example, the third harmonic or higher will be greatly attenuated.
In the diode limiter of the reproduction nonlinear de-emphasis circuit, unnecessary components of the third harmonic or higher are generated, which are severely attenuated, and especially in this case, there is a problem of signal distortion of the reproduced video signal. This is especially true when recording and reproducing multi-burst signals or sin 2 2T pulse signals, where problems arise where sine waves are distorted or 2T pulses are distorted by harmonics.

本発明は以上のような欠点をなくしたものであ
り、非線形エンフアシス回路後でFM変調器前、
非線形デイエンフアシス後から映像信号出力端ま
での間に前記奇数次高調波を除去する回路を挿入
することにより、容易に不要成分を除去し、信号
歪をも除去するようにしたものである。 The present invention eliminates the above-mentioned drawbacks, and includes the following: after the nonlinear emphasis circuit, before the FM modulator,
By inserting a circuit for removing the odd harmonics between after nonlinear de-emphasis and the video signal output end, unnecessary components and signal distortion can be easily removed.

第７図以降に本発明の一実施例を示し説明す
る。第７図において、第１図と同一番号は同一の
動作をするものである。入力端１からの映像信号
はAGC回路を通つて低域ろ波器３で例えば記録
所望帯域Xが3MHzに制限され色信号が除去され、
非線形エンフアシス回路４で入力映像信号の大き
さに応じ、高域周波数成分の強調度が変化され、
高域減衰器２７で、所望の高域周波数以上の成分
が減衰せしめられ、エンフアシス回路５で高域周
波数がさらに強調され、た後、クランプ回路６で
クランプされ、ホワイト側とダーク側がクリツプ
されないか、わずかにクリツプする程度のクリツ
プ回路でクリツプされ、FM変調器８で周波数変
調され、この周波数変調された映像信号は、高域
ろ波器９を通り、記録増幅器１０で増幅されたの
ち、ビデオヘツド１１により記録媒体に記録され
る。この記録回路の前記減衰器２７についてさら
に詳しく説明する。今低域ろ波器３の遮断周波数
をp、高域減衰器２７の遮断周波数をQとする。
さらに記録所望帯域Xは低域は波器３で決まつて
いるとする。本発明においてはQ≧pのある所望
値にQが設定される。今説明の都合上、Q＝pと
して説明する。例えばp＝Q＝3MHzとすると、
FM変調器に入力される映像信号の高調波成分
は、（2n−１）s＜Q……(1)式但し、ｎは２以上
となる。又折りかえし周波数成分が問題となるの
は、前述のごとき、(2)式を満足する成分である。 An embodiment of the present invention will be shown and described from FIG. 7 onwards. In FIG. 7, the same numbers as in FIG. 1 indicate the same operations. The video signal from the input terminal 1 passes through the AGC circuit and is passed through the low-pass filter 3, where the desired recording band X is limited to, for example, 3MHz, and color signals are removed.
The nonlinear emphasis circuit 4 changes the degree of emphasis of high frequency components according to the magnitude of the input video signal,
The high frequency attenuator 27 attenuates components higher than a desired high frequency, the emphasis circuit 5 further emphasizes the high frequencies, and the clamp circuit 6 then clamps the components to ensure that the white and dark sides are not clipped. The video signal is clipped by a clip circuit with a slight clip, and then frequency modulated by an FM modulator 8. This frequency modulated video signal passes through a high-pass filter 9, is amplified by a recording amplifier 10, and then outputs a video signal. The head 11 records on the recording medium. The attenuator 27 of this recording circuit will be explained in more detail. Let us now assume that the cutoff frequency of the low-pass filter 3 is p, and the cutoff frequency of the high-pass attenuator 27 is Q.
Furthermore, it is assumed that the low range of the desired recording band X is determined by the wave generator 3. In the present invention, Q is set to a certain desired value of Q ≧p. For convenience of explanation, let's assume Q = p. For example, if p = Q = 3MHz,
The harmonic components of the video signal input to the FM modulator are (2n-1)s< Q (1), where n is 2 or more. Also, the loopback frequency component that becomes a problem is the component that satisfies equation (2) as described above.

C（2n−１）s＜０……(2)式 さらに搬送波周波数Cは、C＞p……(3)式の関
係に設定されるので、(1)，(2)，(3)式を満足するs
は存在せず、それゆえ折り返しスペクトラムによ
り復調される映像信号に、入力周波数と異なる周
波数の不要成分はなくなる。又、上記説明ではQ
＝pとして説明したが、実際にはCがpに対しど
れだけ高い周波数であるかにより、Qの遮断周波
数は、pよりもある所望値だけ高い周波数に設
定できる。そのようにすれば、帯域制限された低
域ろ波器３で決まる帯域となり、リンギングなど
が増加せず不要成分を除去することができる。 C (2n-1)s<0...Equation (2) Furthermore, the carrier frequency C is set to the relationship of C > p...Equation (3), so Equations (1), (2), and (3) satisfy s
Therefore, the video signal demodulated by the folded spectrum does not contain unnecessary components at frequencies different from the input frequency. Also, in the above explanation, Q
=p, but in reality, depending on how high the frequency of C is relative to p, the cutoff frequency of Q can be set to a frequency higher than p by a certain desired value. In this way, the band is determined by the band-limited low-pass filter 3, and unnecessary components can be removed without increasing ringing.

さてこのように記録された信号を再生するにあ
たつては、ビデオヘツド１１からの再生信号が前
置増幅器１２で増幅され、高域ろ波器１３、リミ
ツタ１４、周波数復調器１５、低域ろ波器１６に
より再生映像信号が得られ、デイエンフアシス回
路１７で高域周波数成分が抑圧され、非線形デイ
エンフアシス回路１８でさらに信号内容に応じ
て、高域周波数成分が抑圧され、ノイズ軽減回路
１９でさらにノイズが軽減れ、高域減衰器２８
で、信号歪や帯域外の不要成分が除去され、出力
端２０に再生映像信号が得られる。この再生回路
においての本発明の要部を説明する。 Now, when reproducing the signal recorded in this way, the reproduced signal from the video head 11 is amplified by the preamplifier 12, and is then amplified by a high-pass filter 13, a limiter 14, a frequency demodulator 15, and a low-frequency A reproduced video signal is obtained by the filter 16, high frequency components are suppressed by the de-emphasis circuit 17, high frequency components are further suppressed by the non-linear de-emphasis circuit 18 according to the signal content, and further by the noise reduction circuit 19. Reduces noise, high frequency attenuator 28
Then, signal distortion and unnecessary components outside the band are removed, and a reproduced video signal is obtained at the output end 20. The main parts of the present invention in this reproducing circuit will be explained.

今低域ろ波器１６の遮断周波数をRとする。こ
のRは原理的には、FM復調器１５が通常パルス
カウント方式といわれる再生搬送波周波数Cから
2Cに変換されて復調されるので、2Cが除去でき
る高い周波数のRにすればよいが、実際にはキヤ
リアバランスとの関係で、C近傍（例えば３〜
5MHz）に選定される。さて、前記高調波の折り
かえし成分が問題となる領域の周波数s成分は、
奇数次高調波が高域減衰器で減衰せしめられて
FM変調されて記録されるので復調された信号は
周波数s成分だけである。 Now let R be the cutoff frequency of the low-pass filter 16. In principle, this R is determined by the FM demodulator 15 from the reproduced carrier frequency C , which is usually called a pulse count method.
Since it is converted to 2C and demodulated, it is best to set R to a high frequency that can remove 2C , but in reality, due to the carrier balance, it is necessary to set R near C (for example, 3 to 3).
5MHz). Now, the frequency s component in the region where the folded harmonic component becomes a problem is:
Odd harmonics are attenuated by a high-frequency attenuator.
Since the signal is FM modulated and recorded, the demodulated signal is only the frequency s component.

つまり不要成分も奇数次高調波もない信号が、
低域ろ波器１６に再生される。しかしながら非線
形デイエンフアシス回路１８に含まれる非線形素
子により再び奇数字高調波を発生し、この周波数
s信号は（2n−１）sの成分を持つ信号になつて
しまう。 In other words, a signal without unnecessary components or odd harmonics is
The signal is reproduced by the low-pass filter 16. However, the nonlinear element included in the nonlinear de-emphasis circuit 18 generates odd number harmonics again, and this frequency
The s signal becomes a signal with (2n-1)s components.

具体的に説明すると、今p＝Q＝3MHzC＝
4.5MHz 高調波の折りかえし成分が発生する領
域は C−（2n−１）s＜０であるから s＞C／2n−１＝4.5／2n−１……(4)式となる。 To explain specifically, now p = Q = 3MHz C =
Since the region where the folded components of the 4.5MHz harmonics occur is C - (2n-1)s<0, s> C /2n-1=4.5/2n-1...Equation (4) is obtained.

(4)式でｎ＝２が３次歪である。ｎ＝２とする
と、sは(5)式 s＞1.5MHz ……(5)式 となる。(5)式を満足する信号sの奇数次高調波は
すべてQより高く減衰されるので、復調された信
号は周波数s成分のきれいな信号である。これが
非線形素子により再び（2n−１）s成分となり、
例えばs＝1.5MHzでは３次歪4.5MHz，５次歪
7.5MHz……を発生する。フーリエ関数からも明
らかなように高次になるほどそのレベルは小さく
なることはいうまでもない。そのため高次高調波
でもつともレベルの大きいものは、３次歪であ
り、これは非線形エンフアシスや非線形デイエン
フアシス回路に入力される信号レベルあるいは使
用する非線形素子により異なるが信号成分に対し
最悪時−20〜−25dB程度であり、大きな信号歪
となる。さらにノイズ軽減回路１９が設けられる
ものでは、さらにこの中のダイオードの非線形に
より奇数次高調波は強調される。 In equation (4), n=2 is third-order distortion. When n=2, s becomes the equation (5) s>1.5MHz ......the equation (5). Since all the odd harmonics of the signal s that satisfy equation (5) are attenuated higher than Q , the demodulated signal is a clean signal of the frequency s component. This becomes the (2n-1)s component again by the nonlinear element,
For example, when s=1.5MHz, third-order distortion is 4.5MHz, fifth-order distortion
Generates 7.5MHz... Needless to say, as is clear from the Fourier function, the higher the order, the smaller the level. Therefore, the highest level of high-order harmonics is third-order distortion, which varies depending on the signal level input to the nonlinear emphasis or nonlinear de-emphasis circuit or the nonlinear element used, but in the worst case, it varies from -20 to This is about -25dB, resulting in large signal distortion. Furthermore, in the case where a noise reduction circuit 19 is provided, odd-numbered harmonics are further emphasized due to the nonlinearity of the diode in the noise reduction circuit 19.

それゆえ高域減衰器２８では、このような高次
高調波を除去するものである。つまり再生所望帯
域本発明の説明では3MHz、以上の高域周波数を
減衰させるようにすれば、上記奇数次高調波が容
易に除去でき信号歪もない高品質の画質が得られ
る。 Therefore, the high-frequency attenuator 28 removes such high-order harmonics. In other words, in the description of the present invention in the desired reproduction band, if high frequencies of 3 MHz or higher are attenuated, the above-mentioned odd harmonics can be easily removed and a high quality image without signal distortion can be obtained.

次に、折り返しの問題とならない状態の信号周
波数sについて考える。今高域減衰器２８の遮断
周波数をTとする。又、R＝T＝3MHzとすると、
周波数sの信号は1MHz以上では３次以上は略々
帯域外となる。又s＜1MHz以下においては、（2n
−１）sの奇数次高調波をもつた信号が復調され
るが、実際系では、第２図のダイオードリミツタ
D1，D2に抵抗が挿入される。これはダイオード
非導通時のC2とダイオード間の電位を安定にす
るためであり、その場合、低周波領域では、ダイ
オードにかかる振幅が小さいため、奇数次歪は非
常に小さいものであり問題とならず、数百ＫHz〜
1MHz成分についてはある程度奇数次歪をもつが、
５次，７次以上は高域減衰器で減衰し、それ以内
の帯域内の奇数次歪は非線形デイエンフアシス回
路の逆変換器である程度軽減される。 Next, consider the signal frequency s in a state where there is no problem with aliasing. Let T be the cutoff frequency of the high-frequency attenuator 28. Also, if R = T = 3MHz,
For a signal with a frequency of s, at 1 MHz or higher, the third and higher orders are almost out of the band. Also, when s<1MHz or less, (2n
-1) A signal with odd harmonics of s is demodulated, but in a practical system, the diode limiter shown in Figure 2
Resistors are inserted into D 1 and D 2 . This is to stabilize the potential between C 2 and the diode when the diode is not conducting. In this case, in the low frequency region, the amplitude applied to the diode is small, so the odd-order distortion is very small and does not pose a problem. Not several hundred KHz~
The 1MHz component has some odd-order distortion, but
The 5th and 7th orders and above are attenuated by a high-frequency attenuator, and odd-order distortion within the band is reduced to some extent by an inverse transformer of a nonlinear de-emphasis circuit.

高域減衰器２８は、説明上、非線形デイエンフ
アシス回路及びノイズ軽減回路１９で発生する
（2n−１）sの奇数次歪を同時に除去するのが望
ましいため、ノイズ軽減回路１９と出力端２０の
間に設置したが、基本的には非線形デイエンフア
シス回路１８と出力端２０間の適切な場所に設置
すればよい。同様に記録系の高域減衰器２７も、
非線形エンフアシス回路４とFM変調器８間の適
切な位置に入れればよい。 The high-frequency attenuator 28 is provided between the noise reduction circuit 19 and the output terminal 20 because it is desirable to simultaneously remove (2n-1)s odd-order distortion generated in the nonlinear de-emphasis circuit and the noise reduction circuit 19. Basically, it may be installed at an appropriate location between the nonlinear de-emphasis circuit 18 and the output end 20. Similarly, the high frequency attenuator 27 of the recording system also
It may be placed at an appropriate position between the nonlinear emphasis circuit 4 and the FM modulator 8.

又、高域減衰器２８を第８図に示すように、非
線形デイエンフアシス回路内の負帰還ループ内、
（一実施例ではＧ（ｓ）と反転器の間に設けて示し
てある。）に設けてもよい。 In addition, as shown in FIG.
(In one embodiment, it is shown as being provided between G(s) and the inverter.)

信号歪を改善するのに重点を置けば再生系の高
域減衰器だけでも、マルチバーストやsin22T信
号の信号歪は大幅に改善される。より高品質を期
待する時は記録系及び再生系共に高域減衰器を用
いると不要成分や信号歪のない高品質の再生画像
を得ることができる。 If you focus on improving signal distortion, the signal distortion of multiburst and sin 2 2T signals can be significantly improved just by using a high-frequency attenuator in the reproduction system. When higher quality is expected, high-frequency attenuators are used in both the recording system and the reproduction system, making it possible to obtain high-quality reproduced images without unnecessary components or signal distortion.

非線形エンフアシスや回路や非線形デイエンフ
アシス回路では、映像信号が小入力振幅時には非
線形素子が非導通であるため、前述の（2n−１）
s成分は全く発生せず画質劣化は全くないが、中
あるいは大信号入力時には（2n−１）s成分が発
生するが本発明により容易に除去でき、振幅的に
中，高振幅の高域エネルギーの多い、マルチバー
ストやsin22Tやモノスコ信号あるいは映像信号
の中，高振幅の輪郭部成分で問題であつた、信号
歪や不要成分を大幅に減少させることができ高品
質の画像を得ることができる。 In non-linear emphasis circuits and non-linear de-emphasis circuits, when the input amplitude of the video signal is small, the non-linear elements are non-conducting, so the above (2n-1)
The s component does not occur at all, and there is no deterioration in image quality. However, when a medium or large signal is input, the (2n-1) s component occurs, but it can be easily removed by the present invention, and the high frequency energy of medium and high amplitudes can be removed. Signal distortion and unnecessary components, which are problems with high-amplitude contour components in multi-burst, sin 2 2T, monoscot signals, or video signals, which often have a lot of noise, can be significantly reduced and high-quality images can be obtained. I can do it.

周波数Tの設定にあたつては、キヤリアもれの
ない範囲でできるだけ高帯域に低域ろ波器１６の
遮断周波数Rを選定しておき、奇数次高調波除去
および再生所望帯域Wを前記Tで規定するように
してもよく、この方法は再生ノイズが比較的少な
いものに適する。なぜなら非線形素子のスレツシ
ヨルドがノイズで誤動作する点からである。又、
再生所望帯域WをRで規定し、高域減衰器２８又
は２９の遮断周波数TをR＝Tか所定値だけ高い
T＞Rのある値に、高次高調波減衰を考慮して決
めればよい。 When setting the frequency T , select the cut-off frequency R of the low-pass filter 16 as high as possible within the range without carrier leakage, and set the desired odd harmonic removal and reproduction band W to the above T. This method is suitable for cases where reproduction noise is relatively small. This is because the threshold of the nonlinear element malfunctions due to noise. or,
The desired reproduction band W is defined by R , and the cutoff frequency T of the high-frequency attenuator 28 or 29 is set to R = T or a predetermined value higher.
It is sufficient to decide on a certain value of T > R by taking into account high-order harmonic attenuation.

以上のように本発明によれば、記録系で小信号
振幅ほど高域周波数を強調し、FM変調器前に、
所望帯域以上の高次高調波を減衰させて記録し、
再生時小信号振幅ほど高域周波数を抑圧する逆変
換器を具備し、その後の系に所望帯域以上の高域
成分を減衰させる高域減衰器を具備することによ
り、高Ｓ／Ｎでしかも高品質の再生画像を得るこ
とができる。又本発明では非線形回路として第２
図や第５図を１列として示したが、小信号ほど高
域成分が強調又は抑圧できるようなものであれば
どのような構成でもよい。さらに本発明を適用で
きるものとしては記録再生系の映像信号の主信号
経路に非線形素子をもつものなどにすべて適用で
きる。 As described above, according to the present invention, the recording system emphasizes higher frequencies as the signal amplitude becomes smaller, and before the FM modulator,
Attenuates and records higher-order harmonics above the desired band,
Equipped with an inverse converter that suppresses high frequency components as the amplitude of the signal becomes smaller during reproduction, and a high frequency attenuator that attenuates high frequency components above the desired band in the subsequent system, it is possible to achieve high S/N and high frequency. You can get quality playback images. In addition, in the present invention, the second nonlinear circuit is
Although the figures and FIG. 5 are shown as one row, any configuration may be used as long as the higher frequency components of the smaller signals can be emphasized or suppressed. Further, the present invention can be applied to all devices having a nonlinear element in the main signal path of a video signal in a recording/reproducing system.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は従来の記録再生装置の１例を示すブロ
ツク図、第２図は同要部の具体構成を示す回路
図、第３図および第４図は同動作説明図、第５図
は非線形デイエンフアシス回路の１例を示すブロ
ツク図、第６図は同動作説明図、第７図は本発明
の１実施例を示すブロツク図、第８図は本発明の
他の実施例の要部を示すブロツク図である。 ２……自動利得制御回路、３，１６……低域ろ
波器、４，２４……非線形エンフアシス回路、５
……エンフアシス回路、６……クランプ回路、７
……クリツプ回路、８……FM変調器、９，１３
……高域ろ波器、１０……記録増巾器、１２……
前置増巾器、１４……リミツタ、１５……FM復
調器、１７……デイエンフアシス回路、１８……
非線形デイエンフアシス回路、１９……ノイズ軽
減回路、２３……増巾器、２５……反転回路、２
８，２９……高域減衰器。 Fig. 1 is a block diagram showing an example of a conventional recording/reproducing device, Fig. 2 is a circuit diagram showing the specific configuration of the main parts, Figs. 3 and 4 are explanatory diagrams of the same operation, and Fig. 5 is a nonlinear device. FIG. 6 is a block diagram showing one example of a de-emphasis circuit, FIG. 6 is an explanatory diagram of the same operation, FIG. 7 is a block diagram showing one embodiment of the present invention, and FIG. 8 is a main part of another embodiment of the present invention. It is a block diagram. 2...Automatic gain control circuit, 3, 16...Low pass filter, 4, 24...Nonlinear emphasis circuit, 5
...Emphasis circuit, 6...Clamp circuit, 7
... Clip circuit, 8 ... FM modulator, 9,13
...High-pass filter, 10...Recording amplifier, 12...
Preamplifier, 14... limiter, 15... FM demodulator, 17... de-emphasis circuit, 18...
Nonlinear de-emphasis circuit, 19... Noise reduction circuit, 23... Amplifier, 25... Inversion circuit, 2
8, 29...High frequency attenuator.

Claims (1)

【特許請求の範囲】 １ 映像信号を周波数変調して、記録媒体に記録
再生し、再生された周波数変調波を周波数復調し
て再生映像信号を得る映像信号記録再生装置であ
つて、映像信号の記録と再生回路に、記録時には
入力レベルが小さい程高域を強調する特性の非線
形素子を含む非線形回路を設け、再生時には、前
記特性の逆の特性を有する非線形回路を設け、少
なくとも再生回路の非線形回路内か後に、再生所
望帯域以上の所定の遮断周波数をもつ高域減衰器
を設け、帯域外の不要成分を減衰させるようにし
たことを特徴とする映像信号記録再生装置。 ２ 高域減衰器が映像信号の記録回路の非線形回
路後と周波数変調器間にも設けられることを特徴
とする特許請求の範囲第１項に記載の映像信号記
録再生装置。 ３ 非線形素子を含む非線形回路が負帰還増幅器
で構成され、その負帰還ループ内に高域減衰器が
設けられることを特徴とする特許請求の範囲第１
項に記載の映像信号記録再生装置。 ４ 高域減衰器の遮断周波数Tが、再生所望帯域
に相当する遮断周波数Wに対し、T≧Wの関係の
遮断周波数に設定されることを特徴とする特許請
求の範囲第１項に記載の映像信号記録再生装置。 ５ 搬送周波数Cとした時、高域減衰器の遮断周
波数Qが、映像信号の記録回路の所望帯域に相当
する遮断周波数Xに対し、C＞Q≧Xの関係を満
足する所定値に設定されることを特徴とする特許
請求の範囲第２項に記載の映像信号記録再生装
置。[Scope of Claims] 1. A video signal recording and reproducing device that frequency-modulates a video signal, records and reproduces it on a recording medium, and demodulates the frequency of the reproduced frequency modulated wave to obtain a reproduced video signal. The recording and reproducing circuits are provided with a nonlinear circuit including a nonlinear element having a characteristic that emphasizes high frequencies as the input level becomes smaller during recording, and a nonlinear circuit having a characteristic opposite to the above characteristic during reproduction is provided, at least within the nonlinear circuit of the reproducing circuit. A video signal recording and reproducing apparatus characterized in that a high-frequency attenuator having a predetermined cut-off frequency higher than a desired reproduction band is provided after that to attenuate unnecessary components outside the band. 2. The video signal recording and reproducing apparatus according to claim 1, wherein a high-frequency attenuator is also provided after the nonlinear circuit of the video signal recording circuit and between the frequency modulator. 3. Claim 1, characterized in that the nonlinear circuit including the nonlinear element is constituted by a negative feedback amplifier, and a high-frequency attenuator is provided in the negative feedback loop.
2. The video signal recording and reproducing device described in 2. 4. The cut-off frequency T of the high-frequency attenuator is set to a cut-off frequency that satisfies the relationship T ≧ W with respect to the cut-off frequency W corresponding to the desired reproduction band. Video signal recording and playback device. 5 When the carrier frequency is C , the cutoff frequency Q of the high-frequency attenuator is set to a predetermined value that satisfies the relationship C > Q ≧ X with respect to the cutoff frequency X corresponding to the desired band of the video signal recording circuit. The video signal recording and reproducing apparatus according to claim 2, characterized in that:
JP6359980A 1980-05-13 1980-05-13 Video signal recorder and reproducer Granted JPS56159810A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP6359980A JPS56159810A (en) 1980-05-13 1980-05-13 Video signal recorder and reproducer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP6359980A JPS56159810A (en) 1980-05-13 1980-05-13 Video signal recorder and reproducer

Publications (2)

Publication Number Publication Date
JPS56159810A JPS56159810A (en) 1981-12-09
JPH0353715B2 true JPH0353715B2 (en) 1991-08-15

Family

ID=13233894

Family Applications (1)

Application Number Title Priority Date Filing Date
JP6359980A Granted JPS56159810A (en) 1980-05-13 1980-05-13 Video signal recorder and reproducer

Country Status (1)

Country Link
JP (1) JPS56159810A (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60121A (en) * 1983-06-15 1985-01-05 Fujitsu Ltd Driving circuit of modulator
JPS60150661U (en) * 1984-03-19 1985-10-07 三洋電機株式会社 video tape recorder
JPS63144457A (en) * 1986-12-09 1988-06-16 Canon Inc Frequency modulator
JPH02301277A (en) * 1989-05-15 1990-12-13 Toshiba Corp Recording processing circuit for video signal

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS49121511A (en) * 1973-03-20 1974-11-20

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS49121511A (en) * 1973-03-20 1974-11-20

Also Published As

Publication number Publication date
JPS56159810A (en) 1981-12-09

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